Hemodialysis is one of the most common treatments provided in medical facilities today, and the market for such treatments continues to grow. The 2013 global dialysis market is valued at $61.60 billion and is expected to grow at a compound annual growth rate (CAGR) of 6.2% over the next five years with the increasing number of end stage renal disease (ESRD) patients and the rising prevalence of diabetes and hypertension worldwide. In addition, growth in the number of dialysis facilities in developed as well as developing markets, increasing private investments, and venture funding to support new product development is contributing to the growth of the global market. Reduced insurance disbursements to dialysis centers, high treatment costs, and low awareness of kidney related diseases and their treatment modalities are factors that continue to restrain market growth.
Hemofiltration is typically employed with patients exhibiting acute kidney injury. In hemofiltration, water and relatively low molecular weight components (up to 20-30 kDa) are removed by convection through a hemofiltration membrane. Water and electrolytes are replaced in the patient. Hemofiltration may be combined with hemodialysis.
FIG. 1 shows an illustrative schematic of a conventional hemodialysis system and technique. In the illustrated system blood is passed from the patient via an appropriate conduit (11) by action of pump (3) into a dialyzer unit (5) which contains an appropriate filter (2), typically a hallow fiber filter, to selectively remove toxic species from the blood. Fresh dialysate is passed, employing pump (7), into the dialyzer via appropriate conduit (14) and used dialysate exits the dialyzer unit via appropriate conduit (12). A dialysate source (22) and waste receptacle (21) are optionally provided. Cleaned blood is returned to the patient via appropriate conduit (13) through an air detector and trap (9). In flow pressure into the dialyzer, venous pressure and arterial pressure are monitored (4, 6 and 8, respectively). A source of saline (16) and heparin (17) are provided via saline conduit (15) as needed via valves or related fluid metering devices (18 and 19) to prevent clotting. FIG. 2 shows an expanded schematic of a conventional hemodialysis membrane (30), having pores (32) of selected dimension to allow passage of ions (33), small molecules (34) and prevent passage of larger macromolecules (35). The thickness (t) of the convention membrane is in the range of 50 micron. Current state solutions, or dialyzers, are hollow fiber membrane (30) devices in a hard plastic shell. Blood flows through the lumen of the fiber and dialysate flows through the dialyzer on the exterior of the fibers. Fibers are traditionally made of porous materials such as cellulose triacetate, polysulfone, polyethersulfone, polymethylmethacrylate, polyester polymer alloy, ethylene vinyl alcohol copolymer or polyacrylonitrile. The fibers have a microporous structure that allows small molecules to diffuse from the blood into the dialysate. The diffusion rate can be expressed in terms of the dialyzer clearance of the molecules. Clearances of various molecules can occur at different rates under various blood and dialysate flow rate conditions. The large variety of dialyzer configurations permits physicians to appropriately specify a hemodialysis treatment to meet the needs of a patient. There is an entire system built around this filter technology to provide the current standard of care to patients. However, the performance is limited by the permeability, selectivity and roughness of the dialyzer membrane.
In view of the foregoing, improved hemodialysis membranes and hemofiltration membranes and methods would be of considerable benefit in the art. In particular, hemodialysis membranes and hemofiltration membranes having increased permeability and selectivity would be especially advantageous. The present disclosure satisfies the foregoing needs and provides related advantages as well.